| A rehabilitation and repair technique with external steel collars was investigated for reinforced concrete short columns through experiment and finite element analysis. Ten cantilever short columns, including two control columns without steel collars and eight rehabilitated columns confined externally by steel collars, have been constructed and tested under combined axial and lateral loading. Parameters considered in the experimental program include collar spacing, collar stiffness, longitudinal reinforcement ratio, axial compression index, pretension of collar bolts, and shear span-to-depth ratio. One control column was tested to failure and then repaired to study the feasibility of using external steel collars on previously damaged columns. The experimental results have shown excellent improvements in the ductility, strength, and energy dissipation capacity of the columns due to the presence of the collars. Three-dimensional finite element models were developed using the finite element program ABAQUS Explicit to further investigate the behaviour of these externally confined columns. Experimental results and finite element analysis have shown that this rehabilitation technique has great promise as an effective procedure for rehabilitation of deficient reinforced concrete short columns.;Research was also conducted with other existing analytical approaches and an improved sectional strength model was proposed for reinforced concrete columns with external steel collars. Finally, design guidelines were proposed for the rehabilitation of reinforced concrete columns along with design examples to illustrate the design guidelines. |
